Strange Update Panel Issue with Devexpress Controls

[wisnu80]

I have some strange issue with Update Panel.I am using Devexpress Controls, JQUERY AJAX in one of my applications. I have used Server side coding + Client side coding aproach i.e. using Jquery, JS and AJAX + Update Panel on some pages where aspxgridview is there.I am creating a scenario via example situation according to the problem I have faced:1) There are some ASPxcomboBoxes for e.g.County, State and City.2) On client Selected index change of Country, I have fetched the data via AJAX and bind the states in State ASPxComboBox using JSON and same for the city combo on client index change of State.3) On the city combo's index change, I have bound a ASPxGridView with some related data and ASPxGridView and City combo is wrapped in Update Panel as we cannot bind the ASPxGridView via AJAX so to avoid postbacks I have used update panel and its working fine.4) If user doesn't selects any record from the Grid on submit click then its prompts the user that select any one record and I have kept the validation on server side button's click event.Now, The problem is after submiting and validation occurs. The State's combos items are repeating for e.g. initial items were : --select--, USA and after validation occurs on submit its showing --select--, USA, --select--, USA.I have not bind the control on page load event as its binded via client side. The property of EnableSynchronisation is True to synchronise client and server items of aspxComboBox.When I saw using debugger when I click on submit. I have quick watched State combo and its items count is 4 as 2 are repeatative items.When I remove Update panel, everything works fine.I don't know why wrong items/ repeatative items are posted on server. Please help.